Exam 2 Lecture - Developmental Anatomy Flashcards
What are congenital defects?
defects that are present at birth
What can cause congenital defects?
anything that the mother comes in contact with can affect the pregnancy; environmental, vaccines, medicines
What is a critical period of development?
a point in time when we have an organ or an organ system developing
When is a fetus the most susceptible to environmental influences?
during critical periods because they are undergoing a lot of replication
What can disruption in one organ system lead to?
can impact the development of another organ systems
True or False: Critical periods only occur in utero
False: they can occur post natally
What is the cause of cycloptic lamb?
the ewe ingests the veratrum californicum at 14-15 days of gestation that can cause this defect
What could cause cerebellar hypoplasia?
genetic reasons, infections, toxins
Specifically: bovine viral diarrhea and feline panleukopenia
How can bovine viral diarrhea cause cerebellar hypoplasia?
If the cow is infected with BVD within 100-170 days of gestation the calf could be infected which in turn will cause cerebellar hypoplasia
How can feline panleukopenia cause cerebellar hypoplasia?
If the queen gets infected with feline panleukopenia in the last part of gestation or the kitten gets infected within the first 14 days of birth the kitten can develop cerebellar hypoplasia
Cells in the zygote are____.
(A) restricted
(B) unrestricted
unrestricted
Why do cells become more restricted throughout development?
because their environment is changing and the cells that they are in contact with are changing
True or False: Cells have the same DNA later in development that they had in early development
True: although the cells are more restricted later in development, their DNA does not change
What is a zygote?
a really big cell
What is the zona pellucida?
the glycoprotein covering that surrounds the zygote
What is a cleavage?
it is where the zygote divides
True or False: When the cell continues to divide, and the zona pellucida is still in place, the zygote grows to make space for the new cells
False
When does the zygote become the morula?
when there are 16 blasomeres present
What do the outer blastomeres of the morula become?
trophoblast cells which help form part of the placenta
What do the inner blastomeres of the morula become?
contribute to the inner cell mass - embryo
What blastomeres are the target of embryonic splitting
the inner blastomeres
When does the morula become the blastula?
when the zona pellucida has broken down and the embryo begins to grow
What is the purpose of the blastocoele?
to help facilitate diffusion
When does gastrolation normally occur?
around 14 days into the gestational period
Right before gastolation, what are the structures of the embryo?
amniotic cavity, yolk sac, bilaminar disc (embryo)
What is the bilaminar disc made out of?
epiblast cells and hypoblast cells
What is the purpose of gastrolation?
to give rise to three germ layers and marks the beginning of organ and body development
What initiates gastrolation?
the formation of the primitive streak and the primitive node
What is the importance of the primitive streak aside from initiating gastrolation?
it gives the embryo its polarity
What forms the endoderm?
the wave of epiblast cells that flow deep through the primitive groove
What forms the mesoderm?
the wave of epiblast cells that flow through the primitive groove but lay closer to it than the endoderm
What forms the ectoderm?
the wave of epiblast cells that do not migrate at all
Where is the notochord formed?
in the mesoderm
What does the ectoderm become?
skin, neural tissue, skeletal and connective tissue of the head
What does the mesoderm become?
muscle, skeleton, internal organs (specifically urogenital), cardiovascular season
What does the endoderm become?
the lining of the digestive and respiratory tracts as well as the organs of digestion
What initiates the creation of the coelom?
small vesicles called ceolomic vesicles
Where are coelomic vesicles located?
within the mesoderm
When these vesicles coalesque, what do they form?
the ceolem; the somatic layer and the splanchnic layer
What does the somatic coelem become?
the body wall, adjacent to the ectoderm
How does the somatic coelem grow?
ventrally and medially
What does the splanchnic coelem become?
organs, adjacent to the endoderm, the primitive gut tube
How does the splanchnic coelem grow?
ventrally and medially
What is schistosmomus reflexus?
when the body wall never forms in utero; most common in cattle
What are the 3 situations that can result in monozygotic twinning?
- blastomeres split apart and form 2 completely separate embryos
- two inner cell masses develop (share the same placenta)
- No separation of the zygote or inner mass cells (share amniotic cavity and placenta; can lead to conjoined twins)
What is an amorphous globosus?
a hairy glob of muscle and connective tissue that comes out after a calf has been born
